The FBI is offering $3m (£1.9m) to anyone who can provide information on the alleged gang leader behind the GameOver Zeus network, which was taken down last summer in an international police strike.
Evgeniy Mikhailovich Bogachev is accused of administering to the criminal botnet that hijacked computers around the world in order to steal data and spread the ransomware CryptoLocker, which encrypted data before demanding payment for its release.
"While Bogachev knowingly acted in a role as an administrator, others involved in the scheme conspired to distribute spam and phishing emails, which contained links to compromised web sites," the FBI wrote in the alleged hacker’s entry on its Cyber’s Most Wanted list.
"Victims who visited these web sites were infected with the malware, which Bogachev and others utilized to steal money from the victims’ bank accounts."
The bureau has estimated that financial losses from GameOver Zeus amount to $100m (£64.5), with computers infected with the virus thought to number one million.
Since the botnet was shut down little has been heard of the group behind the two viruses, though one researcher from Cloudmark told CBR they were likely working on other types of ransomware.
Bogachev was indicted by a federal grand jury in Pennsylvania on charges of conspiracy, computer fraud, wire fraud, bank fraud and money laundering last May. His last known location was the Russian town of Anapa, just east and across the sea from Crimea.
